This invention relates in general to gaskets used to provide a seal between two parts, and more specifically to a cylinder bead gasket that is made to be installed between a cylinder head and a cylinder block of an engine, for example. This invention also relates to a method of producing a cylinder head gasket.
Cylinder head gaskets are typically formed from a flat piece of material through which holes are stamped or punched, forming a gasket body. The gasket body is typically a black or dark gray color. The smaller holes are made to align with coolant and oil passages in the engine cylinder block and head. Each of the larger holes surrounds one of the engine cylinder bores. An armor plate is then aligned with the larger holes from one side of the gasket body, with flanges extending through the holes to the other side. The flanges are then formed (bent down around the holes) in order to secure the armor to the gasket body to form the cylinder head gasket. The armor is typically made of metal and provides improved sealing properties around the cylinder bores.
There are drawbacks to the standard method of producing these gaskets that result in gaskets which may provide less long-life fluid sealing performance than is desired. For instance, during the stamping process, flakes of the gasket body material may break free and stick to the gasket body. And, other debris around the location where the gasket is being manufactured may also fall onto and stick to the gasket body. Since the flakes and much of the other debris may be the a similar dark color as the gasket body, the flakes and debris are not noticed during the next steps in the production process. When the armor plate is assembled to the gasket body, then, there is a chance of trapping the flakes or other debris between the armor and the gasket body. This is not desirable since the flakes or other debris trapped during the forming process can make the flange bend unevenly, which can potentially reduce the sealing effectiveness of the gasket.
Moreover, once in service, should a gasket need replacing—for example, during an engine re-build—the gasket body material generally used for cylinder head gaskets tends to stick to the surfaces of the cylinder block and head. This is undesirable and tends to increase the time for proper replacement of the cylinder head gasket needed to assure good long-life sealing performance.
Also, since the gasket body is made from a dark material, if one needs to analyze a gasket removed from a vehicle due to potentially poor sealing performance, it can be difficult to locate a fluid leak path. Locating a fluid leak path and analyzing its characteristics can help one to better determine a root cause of a gasket leak.
Thus, it is desirable to employ an improved method of producing a cylinder head gasket that will result in an improved gasket that overcomes the drawbacks noted above with cylinder head gaskets used to seal between and engine cylinder block and head.